private void SetShaper(Shaper<RecordState> shaper, CoordinatorFactory<RecordState> coordinatorFactory, int depth)
        {
            _shaper = shaper;
            _coordinatorFactory = coordinatorFactory;
            _dataRecord = new BridgeDataRecord(shaper, depth);

            // To determine whether there are any rows for this coordinator at this place in 
            // the root enumerator, we pretty much just look at it's current record (we'll read 
            // one if there isn't one waiting) and if it matches our coordinator, we've got rows.
            _hasRows = false;

            if (!_shaper.DataWaiting)
            {
                _shaper.DataWaiting = _shaper.RootEnumerator.MoveNext();
            }

            if (_shaper.DataWaiting)
            {
                var currentRecord = _shaper.RootEnumerator.Current;

                if (null != currentRecord)
                {
                    _hasRows = (currentRecord.CoordinatorFactory == _coordinatorFactory);
                }
            }

            // Once we've created the root enumerator, we can get the default record state
            _defaultRecordState = coordinatorFactory.GetDefaultRecordState(_shaper);
            Debug.Assert(null != _defaultRecordState, "no default?");
        }